The clinical practice of acute ischemic stroke is at a critical juncture. The use of dot-removal devices approved by the FDA is rapidly expanding, and more devices are poised to enter clinical practice in next several years. This major change in clinical practice has accelerated since 2004 after the approval of the first FDA-cleared device for thrombus removal in acute stroke patients and is occurring without clinical data demonstrating that these devices improve patient outcome as compared to standard therapy (IV rt-PA within three hours of onset). The ongoing multicenter Interventional Management of Stroke (IMS) III Trial is the only randomized Phase III trial that compares the standard therapy to an approach that combines IV rt-PA followed by lA removal of thrombus by devices and/or lA rt-PA. Data from this Trial are critical to inform clinical and public health policy decisions regarding the roe of endovascular therapy for acute ischemic stroke. The primary objective of the IMS III Trial is to determine if ischemic stroke subjects with a baseline NIHSS scores 10, or with an NIHSSSof 8-9 with evidence of MCA, ICA, or basilar artery occlusion by CTA, treated with the combined IV+IA approach started within 3 hours of onset, are more likely to have a favorable outcome, defined as a modified Rankin Scale score of 0-2 assessed at 90 days from randomization, as compared to subjects treated with standard IV rt-PA. The two treatment groups also are compared with regard to additional clinical outcome measures, imaging, and safety data. In addiiton, cost effectiveness of the combined IV+IA approach is evaluated. The Trial currently is supported by two NINDS cooperative agreement grants: (1) to the University of Cincinnati Clinical Coordinating and Angiographic Imaging Center (PI: Joseph P. Broderick, MD) to provide clinical leadership and project and site management; and (2) to the Statistical and Data Coordinating Center (SDCC) at the Medical University of South Carolina (PI: Yuko Y. Palesch, PhD) to provide data management and statistical expertise. The purpose of this competitive renewal application from the SDCC is to closely collaborate with the Trial investigators to bring the IMS III Trial to successful completion with data quality of the highest standard.